Many professionals rely on tools of their trade in order to carry out their professional tasks, ranging from a technician going to repair a machine to a surgeon entering into a surgery room. These professionals need to confirm that all their required tools are inside their toolbox before they start to work and that when their work is finished, all the tools are put back into the toolbox and no tool is forgotten behind.
In recent years, many systems and methodologies have been developed and implemented to track and control inventory in places such as storage facilities, retail stores, storage cabinets, etc. A common solution is an implementation of a sign-off sheet where the user marks the items that are checked out or returned. Naturally, such manual systems are not very reliable due to human errors and thus cannot be used in cases where high-reliability is essential.
In more recent years, automated, computer-based systems have been introduced to control and track items and inventory. Attaching individual identification means to each item has enabled better tracking of the item at certain points. Barcodes are a very popular mean to identify an item, and scanning the barcode, for example at a retail store cash register, enables to identify the item. Barcodes are very popular due to their availability, low cost and simple implementation. As widespread as they are, barcodes have limitations. They require line of sight access to an optical scanner. Reading a barcode often requires human interaction to position the scanner or the coded item. A barcoded item can only convey the original information carried in the code, and cannot be updated in any way. A barcode's size effectively limits the amount of data that can be stored on it.
Radio Frequency Identification tags (RFID) represent a significant improvement compared to barcode technology. Rather than using visible light as a communication medium, RFID technology uses radio waves. Rather than using an optical scanner, the RFID application uses a 2-way radio, known as a reader. Rather than having data encoded on a visual barcode, an item tracked with RFID technology has affixed to it a small computer chip with the capacity to contain far more data than a barcode. In addition, the chip is equipped with an antenna which allows it to both send and receive data.
The chip, antenna and casing together are known as an RFID tag. When a tagged item is close enough to an RFID reader, the reader electronically induces the tag to send the data on its chip to the reader using its antenna. Since radio waves pass through most materials, no line of sight is necessary.
The Electronic Product Code (EPC) is used for identifying the object to which the tag is attached. The EPC has a 96-bit capacity and is made up of a header that gives information on the length of the EPC number, the type and version of code. The header requires 8 bits of memory; the EPC manager requires 28 bits and identifies the manufacturing company; the object class takes 24 bits and classifies the item; and the serial number requires 36 bits and identifies an item within a class. The EPC resides in the chip, the chip is attached to a coiled antenna and this assembly is housed in a packaging best suited to be affixed to the object that has to be monitored.
Tags are classified as active, passive, and semi-passive. Electronic Article Surveillance (EAS) tags used widely in the retail industry are the best examples of passive tags. Tags are also classified in terms of their memory as read only, read/write, and combination tags. Passive tags do not have their own source of energy and use the method known as “energy harvesting” to absorb energy from a reader and use it to transmit the data back to the reader at a different frequency.
Active tags have their own power source but can be read only when they come in the read range of the reader. An internal power source means that active tags have a greater range than passive tags. They can be read from a distance of around 30 yards. However, the inclusion of a battery has increased the weight and cost of active tags and has reduced its life to equal the span of the battery, which currently is around five years.
Semi-passive tags are equipped with a sensor that enables the monitoring of temperature, movement, etc. They are used in situations like cold chains where it is important to track the movement as well as the condition of an item.
The reader has three main components; an antenna, a receiver, and a decoder. The complexity of the readers is a function of the type of tags they are meant to support. The read range is a function of the size and efficiency of the antenna and the transmitter power. The area covered and range of operation increases with the number of antennas. Upon receiving information from a tag in its read range, the reader processes the information in its decoding software and then transmits it to the information management system that it is connected to.
The rate at which data is transferred is directly proportional to the frequency of the radio waves. The variations in the regulations that govern the frequency ranges used in different countries are an impediment to the growth of RFID. The read range of the tag is influenced by the frequency of the radio waves, the power in the tag, the power in the reader, working environment, and antenna size.
Factors that affect the read rates include the type of tags and their placement on the pallet, case, or item; the orientation of the antenna; reader settings, etc. Pilots conducted in controlled conditions are very often inaccurate indicators of tag-reader performance. Sources of interference in actual work conditions include cell phones, walkie-talkies, metals, liquids, etc.
There is a need in the art to provide a reliable, easy-to-use and cost-effective system that can assure a professional that all his required tools are in the required case both before starting to work and once work is finished.